Content Provider
Biodiversity Heritage Library (BHL)
2
DataCite Metadata Store (German National Library of Science and Technology)
2
Hathi Trust Digital Library
2
Directory of Open Access Journals: DOAJ Articles
1
ETH Zürich Research Collection
1
Georg-August-Universität Göttingen: GoeScholar
1
Memorial University of Newfoundland: Digital Archives Initiative (DAI)
1
Open Research Library
1
ULB Düsseldorf: Digitale Sammlungen (University Library of Düsseldorf University)
1
University of Michigan: Digital Collections
1